1. Field of the Invention
The present invention pertains to a method for making an ultra-high frequency transition between two orthogonal structures and to an ultra-high frequency circuit with a transition of this type.
2. Description of the Prior Art
In ultra-high frequency equipment for radars, it is necessary to use transitions by which an electromagnetic wave, propagated in a plane that shall be called a horizontal plane, is transferred to an orthogonal, i.e. vertical, guide. An elbow-shaped guide section is generally used for this purpose. Usually, at the right angle formed between a vertical wall and a horizontal wall, either a metallic part is added on to close the angle or the said part is machined in the guide. The said part forms a smooth face with a tilt such that the electrical or magnetic field, which is vertical in the horizontal guide, gradually becomes horizontal in the vertical guide.
For equipment intended to work at frequencies of up to 30 or 40 GHz, conventional techniques are used: either parts of the elbow-shaped guide are milled, the slopes are obtained by inclining the part with respect to the milling tool, or an already bevelled part is added on.
For equipment designed to operate at greater frequencies (corresponding, therefore, to millimeter waves) the problem of machining becomes a predominant one for conventional methods are no longer applicable here. The precision to be obtained is all the greater as the dimensions of the guiding walls are small. The tilting movements to which the part must be subjected, in order to cut out the face by milling it, prove to be incompatible with the required tolerances. This is also the case with the method where an already-machined face is added on.
The present invention removes this disadvantage. It can be used to make ultra-high frequency circuits designed to work, in particular, with millimeter-wave applications where the horizontal guide/vertical guide transitions are made by cutting-out operations in the block without its being necessary to tilt the structures.